'I Can't Believe You've Done This' is a legendary internet meme stemming from a 2006 viral video featuring a young British man named Adam. While attempting to record a video, he is suddenly punched in the face by his friend for no apparent reason, leading him to deliver the deadpan, posh response: 'Ah fuck, I can't believe you've done this.' The clip gained massive popularity on platforms like YouTube and Vine due to the contrast between the physical violence and the victim's incredibly calm, disappointed reaction. Today, it remains a staple of reaction imagery, used to express shock or disbelief when someone does something unexpected, traitorous, or mildly inconvenient.